192 



THE CRINO1DEA 



syzygy ; IIBrj united to lax by articulation ; arms isotomous, incorporated 

 in cup at least up to IIBr., ; iBr few and irregular ; the upper columnals 

 widen gradually, and, with the proximale, form a cone passing into the 

 cup (Fig. XVII. 5, 6). Guettardicrinus, d'Orbigny (1840), Upper Jurassic, 

 differs from Apiocrinus only in the union of IIBr 1 to lax by close suture, 

 the incorporation of a greater number of IIBr in the cup, and the presence 



2 1 3 



Fio. CXIII. 



Calamocrinus Diomedcif. 1, the crown and proximal portion of the stem from the right 

 posterior intcrradius, x jj. 2, the root, nat. size. 3, the interior of the basal circlet, from 

 above, showing the anchylosed sutures (S) and the axial cords (cur) radiating from the central 

 chambered organ, x f. (After Agassiz.) 



of more iBr ; it is the acme of this line of development. Acrochordocrinus, 

 Trautschold (1859; synn. Cyclocrinus, d'Orb. non Eichw. ; Mespilocrinus, 

 Quenst. non de Kon.), Jurassic and Lower Cretaceous; columnals only. 

 Calamocrinus, A. Agassiz (1890,-92), 392-782 fathoms, Galapagos Is. and B. 

 of Panama (Fig. CXIII.). Patina distinct, owing to restriction of facet to 

 $ width of R ; BB tend to be fused ; RR laterally united by ligament ; 

 r. and 1. post. RR slightly longer than the others. IBfj united to R by 



